Hello I have a 1986 k5 with a 700r4 and 208c and my issue is when I take off from a dead stop it makes a horrible grinding sound and shake like it's trying to bind up or like slipping splines. I assumed it was the transfercase so I bought a cheap used case. The guy said he thought it was good but couldn't guarantee it. So I put it in and it seems tighter but still there anything over 1/4 throttle still does it. Did I get a bad case or is it something else? Low planetary? I'm lost